Cisco SPA 501G Administration Guide

Configuring Security, Quality, and Network Features
Ensuring Voice Quality
Cisco SPA 500 Series and WIP310 IP Phone Administration Guide 113
5
Bandwidth Requirements
Depending on how you have your IP phones configured, each call requires 55 to
110 kbps in each direction. Therefore, using G.729 as the voice codec setting, and
with an average business-grade broadband Internet connection supporting 1.5
Mbps downstream and 384 kbps upstream, a total of seven (7) simultaneous
conversations can be reliably supported with adequate bandwidth available for
file downloads.
Cisco recommends using the Cisco IP phones with QoS-capable networking
equipment that can prioritize the VoIP application traffic. QoS features are
available on many data networking switches and routers. A QoS-enabled router
prioritizes the packets going upstream to the ISP.
G.726 Low complexity. Supports compressed 16, 24, 32, and
40 kbps digitized voice transmission at one through
ten 10 ms voice frames per packet. When no static
payload value is assigned per RFC 1890, Cisco IP
phones can support dynamic payloads for G.726.
NOTE G.726 is supported only for 32kbps on the SPA
525G.
4.1 (32 kbps)
G.729 and
G.729A
G.729A low-medium complexity. G.729 medium
complexity.
G.729A requires about half the processing power of
G.729. The G.729 and G.729A bit streams are
compatible and interoperable, but not identical.
4
G.723.1 High complexity. Cisco IP phones support the use of
ITU G.723.1 audio codec at 6.4 kbps. Up to two
channels of G.723.1 can be used simultaneously. For
example, Line 1 and Line 2 can be using G.723.1
simultaneously, or Line 1 or Line 2 can initiate a three-
way conference with both call legs using G.723.1.
NOTE G.723.1 is not supported on the 525G or
WIP310.
3.8
G.722 Only one G.722 call at a time is allowed. If a
conference call is placed, a SIP re-invite message is
sent to switch the calls to narrowband audio.
NOTE Not supported on the WIP310.
4.3 (approx)
Codec (Voice
Compression
Algorithm)
Complexity and Description MOS Score

Cisco SPA 501G Specifications

General

Brand	Cisco
Model	SPA 501G
Category	IP Phone
Language	English